The present invention relates to a golf club head capable of changing a depth of the center of gravity without substantially changing a distance of the center of gravity.
Performances of golf club heads change greatly by change of a location of the center of gravity. For example, in case of a golf club head that a depth of the center of gravity which is a distance between the center of gravity of a club head and a sweet spot of a club face, is small, it is easy to change the direction of the club head and, therefore, it is easy to manipulate the direction of hitting a golf ball freely. On the other hand, in case of a golf club head having a large depth of the center of gravity, a straight flight property of a hit ball is high because the direction of the club head is hard to change even at mis-shot.
In recent years, there are proposed golf club heads having a good so-called custom fitting that the depth of the center of gravity can be freely changed in accordance with a condition of a golfer or a course layout. For example, as shown in FIG. 10A, this type of a golf club head “a” is composed of a head body “b” having a concave portion or hole “c” which is opened at a back face, a weight “d” which is inserted into the hole “c”, and a buffer “e” for adjusting the position of the weight inserted. Thus, a depth “f” of the center of gravity (=distance between a center of gravity “g” and a sweet spot “ss”) can be changed to a position that a golfer desires by exchanging the inserting positions between the weight “d” and the buffer “e” as shown in FIGS. 10A and 10B. A similar golf club head is disclosed in JP 2004-159680 A.
This golf club head “a” can change the depth “f” of the center of gravity to a depth “f1” or to a depth “f2” by the position interchange. However, simultaneously, a distance “h” of the center of gravity which is the shortest distance from an axial center line “j” of a shaft-inserting hole “i” to the center of gravity “g” of the head “a”, also changes from a distance “h1” to a distance “h2”. Thus, the moment of inertia of the golf club head about an axis of a shaft also changes with the position interchange. If the distance “h” of the center of gravity is decreased, the moment of inertia of the golf club head about the shaft axis decreases, so the face tends to turn over the address position at the time of impact and hooking of the ball is easy to occur. On the other hand, if the distance “h” of the center of gravity is increased, the moment of inertia of the golf club head about the shaft axis increases, so the face tends to be difficult to return back to the address position at the time of impact and a slice of the ball is apt to occur. Thus, the golf club head “a” as mentioned above has a problem that performances of the golf club greatly alter.
It is an object of the present invention to provide a golf club head, particularly a wood-type golf club head, which is capable of changing a depth of the center of gravity without substantially changing a distance of the center of gravity.
This and other objects of the present invention will become apparent from the description hereinafter.